This invention relates to pick and place equipment in semiconductor manufacturing and more particularly to a tool and method to decide partial wafer sizes to process multiple random size wafers.
The wafermap process eliminates the inking of reject die at the wafer fab by using the map data available from the probe test to position the wafer to exact location of all the good die on the Die Bonder or Tape and Reel. Hence, direct jumps to good die are possible without scanning the whole wafer. See FIG. 1 for a typical wafer.
In wafermapping environment, the wafermap data contains good, bad, plug and edge dies coordinates with reference to a Reference die of a wafer. A Bin in wafermap data is a category of dies. For example, Bin 1 is all good first grade dies, Bin 2 is all good second grade dies, Bin 3 is all Plug dies, Bin 4 is all bad edge dies and Bin 5 is remaining bad dies.
With small die wafers having high chips per wafer count, the wafers are also processed in halves, quarters and other sizes to match the production lot size at the Assembly And Test site. Thus, partial wafer processing is very much an operational requirement for small die wafers unlike large die wafers.
Since each good die is valuable a partial wafer is even more valuable. Partial wafers are formed by cutting a wafer into half (two pieces) or quarter (four pieces) or other different size pieces (multiple pieces). See FIG. 2 for a half pieces, FIG. 3 for quarter pieces and FIG. 4 for other multiple pieces. A fabricator may know how many good dies are needed but with or without wafermap operation, it is difficult to decide for a production demand where to cut a wafer and how many pieces are required. Currently, no known tool exists to perform this type of operation.
In accordance with one embodiment of the present invention a method and tool for deciding and providing a partial wafer size for production demands includes the steps of getting wafermap data, providing the coordinates of the one or more cutters relative to the wafer and moving the one or more cutters relative to the wafer to determine the cut of the wafer to form the desired partial wafer.
In accordance with another embodiment of the present invention the method steps include providing the coordinates of a pair of orthogonal oriented wafer cutters, getting wafermap data of good dies and moving the coordinate positions of the cutters relative to the wafer and displaying the results of the type of dies in each partial that would result from the cut according to said wafermap data.
In accordance with another embodiment of the present invention the tool automatically queries the number of good dies wanted and the type of partial wafer selected and the system automatically decides the cut position or one or more cutters.